JP2020500337A - Adjustable MEMS etalon device - Google Patents

Abstract

The tunable MEMS etalon device is pre-stressed in the initial pre-stressed, non-actuated etalon state, as determined by the rear stopper structure in physical contact with the front and rear mirrors. A front mirror and a rear mirror separated by a gap having a non-working gap dimension, wherein the gap has at least one working state having a working gap dimension that is greater than a pre-stressed non-working gap dimension. A front mirror and a rear mirror, an anchor structure, an anchor structure, a frame structure fixedly connected to the front mirror at a first surface of the front mirror facing the incoming light, wherein the etalon is configured; A bent structure that can be attached to the structure and frame structure but not to the front mirror, and an anchor structure A spacing structure away from Part mirror, front mirror and the spacer structure and a spacer structure formed on the same single glass layer.

Description

  This application claims the benefit of US Provisional Patent Application No. 62 / 424,472, filed November 20, 2016, having the same name and incorporated herein by reference in its entirety.

  The subject matter of the present disclosure relates generally to micro-electro-mechanical systems (MEMS), and more particularly to tunable MEMS-based spectral filters.

  References believed to be relevant as background to the subject of the present disclosure are listed as Non-Patent Documents 1 to 3.

  A review of the above references herein should not be taken to imply that they are in any way related to the patentability of the subject matter of this disclosure.

  Color imaging is commonly known and performed using a color filter array (CFA), for example a digital camera with a pixelated image sensor covered by a Bayer-type CFA. I have. Recently, systems and methods for color imaging using sequential imaging have been proposed. See, for example, commonly assigned US Pat. Such systems and methods allow for the capture of rich images with improved color fidelity and / or hyperspectral color information.

  In general, sequential imaging utilizes an adjustable spectral filter positioned along the line of sight of the camera image sensor. The image sensor operates to acquire a series of images in a short sequence while changing the spectral transmittance of the adjustable spectral filter. Thus, each image in the series corresponds to a different color component of the captured scene, according to the state / profile of the spectral transmittance of the filter set when the respective image was taken.

  An example of an adjustable spectral filter that can be used for sequential imaging as described above is an etalon. The etalon has two parallel mirrors. The spectral transmittance profile is determined by the gap between the mirrors. Adjusting the voltage applied to the etalon adjusts the gap between the mirrors (providing a so-called "optical cavity") and further adjusts the spectral transmittance profile. The two mirrors can be, for example, a transflective front mirror and a transflective rear mirror. In some instances, the rear mirror may be stationary, for example, while the front mirror is directed toward the rear mirror to change the distance between the mirrors (optical cavity) and thereby adjust the spectral transmission profile. It may be movable away from the front / rear mirror.

  Etalons are widely used in optical communications to filter, modulate, and / or control the properties of optical signals, such as laser light beams transmitted along optical communications channels. However, considering optical communications, filters are often required to operate accurately and efficiently only in a limited (eg, a few nanometers) spectral band, often for sequential spectral imaging applications. It is not required to provide a specific / wide transmission profile as described (see, for example, US Pat.

International Publication No. WO 2014/207742 International Publication No. 2017/009850

A. Ya’akobovitz, S. Krylov, “Influence of Perforation on Electrostatic and Damping Forces in Thick SOI MEMS Structures,” J. Micromech. Microeng. 22, pap.115006, 2012. C. G. Agudelo, M. Packirisamy, G. Zhu, L. Saydy, “Nonlinear control of an electrostatic micromirror beyond pull-in with experimental validation,” J. MEMS 18, 914-923, 2009. J. Wei “Wafer Bonding Techniques for Microsystem Packaging,” Journal of Physics: Conference Series 34 (2006) 943-948

  In some imaging applications, such as, for example, normal (eg, RGB) color image data acquisition, IR image data acquisition, and / or high spectral imaging, etalons often have a wide spectral transmittance profile and a wide free spectral range. Not only is it necessary (which can impose a short distance between the mirrors of the etalon), but also laterally enough so that the etalon covers the entire field of view of the image sensor placed in front of it. Wide may be required.

  As a result, tunable etalons for use in sequential spectral color imaging often have very high aspect ratios between their width and the distance between their mirrors.

  Although the general principles of etalon operation are well known, some limiting factors of conventional etalon configurations preclude the use of etalons in sequential spectral imaging applications. One such limiting factor relates to the adjustment range and resolution of the gap between the etalon and the mirror, which is limited in conventional adjustable etalon configurations. As will be described in more detail below, this problem is solved in some instances disclosed herein by providing a novel etalon configuration. Another limiting factor of conventional etalon configurations is that the high performance actuators (actuation and / or feedback mechanisms) used in such etalons are expensive and not suitable for mass production. In contrast, the MEMS-based etalons disclosed herein can be mass-produced at relatively low cost.

  One challenge is manufacturing variability, which will be represented by a distorted transmission spectrum. Thus, the design of the tunable etalon MEMS device disclosed herein is a optomechanical model that estimates reasonable manufacturing tolerances, quantifies spectral distortion, and calibrates the acquired signal accordingly. Developed based on

  In some instances, where electrostatic actuation is used, as disclosed herein, the movement / gap and parallelism between the front and rear mirrors may be adjusted (e.g., to carry an actuating mechanism, A potential difference between two or more regions of an electrode formed on a working layer (with a working substrate that is part of a layer) and substantially electrically isolated from one another, formed on a functional mechanical layer The set of substantially parallel electrodes thus set can be adjusted by causing an electrostatic force between the electrodes. A functional layer is here considered a layer that moves when an actuation force is applied.

  In the example where the electrodes are formed in the handle layer of a silicon-on-insulator (SOI) wafer, the electrodes can be electrically isolated from one another by grooves in the layer.

  The embodiments disclosed herein teach several tunable MEMS etalon architectures and operating paradigms. A common feature in all embodiments is that the front mirror (of the two mirrors facing the incident light) is attached to the functional mechanical layer of the MEMS. The use of MEMS actuators enables low cost mass production of the proposed etalon, making it suitable for mounting on home appliances. According to one example, the attachment of the front mirror to the functional mechanical layer is performed by a pick and place technique, as is known in the art.

  In addition to the features described above, the method according to this aspect of the presently disclosed subject matter may include, in any technically possible combination or permutation, one or more of features (i)-(xix) listed below. Can optionally be present.

  According to one example of the presently disclosed subject matter, there is provided an adjustable etalon device comprising a front mirror and a rear mirror, wherein the front and rear mirrors are pre-stressed in an initial, non-operating etalon state. Separated by a gap having the specified inactive gap dimension. The etalon is configured to assume at least one actuation state wherein the gap has an actuation gap dimension that is greater than a pre-stressed non-actuation gap dimension.

In addition to the features described above, in certain instances, the presently disclosed subject matter may incorporate one or more of features (i)-(xxxiv) listed below in any technically possible combination or permutation. You can have more.
i) The pre-stressed inactive gap size is determined by the rear stopper structure in physical contact with the front and rear mirrors.
ii) The rear stop structure can be formed first on either mirror.
iii) The tunable etalon device disclosed herein is manufactured using MEMS technology, whereby it is also referred to as a tunable MEMS etalon device.
iv) The adjustable etalon device disclosed herein comprises an anchor structure, a frame structure fixedly connected to the front mirror, and the anchor structure and the frame structure attached to the front structure. The apparatus further includes a bending structure that is not attached to the mirror.
v) The tunable etalon device disclosed herein further comprises a spacer structure separating the anchor structure from the rear mirror, wherein the front mirror and the spacer structure are formed in the same single layer. .
vi) The rear mirror is included in a layer made of a transparent or translucent material. In some instances, the transparent or semi-transparent material may be any one of glass, plastic, silicon, and germanium.
vii) The transparent or semi-permeable layer further has a recess to assist in pre-stressing the flexure structure to enhance the pre-stressed inactive state.
viii) The anchor structure, the frame structure, and the bent structure are made of silicon (Si).
ix) A tunable etalon device in which the anchor structure, frame structure, and flexure structure are formed of the same single layer.
x) A tunable etalon device, wherein the single layer is made of one of the following materials: glass, plastic, silicon, and germanium.
xi) The rear mirror is adjustable, integrated in a layer made of a transparent or translucent material (for example comprising any one of glass, plastic, silicon and germanium) Etalon device.
xii) the rear mirror is such that a first of the at least two materials is transparent or semi-transparent and a second of the at least two materials is more rigid than the first material. Tunable etalon device included in a hybrid structure having a combination of at least two materials.
xiii) Tunable etalon devices, where different materials include, for example, glass and silicon.
xiv) an adjustable etalon device further comprising a cap plate located on the object side with respect to the front mirror.
xv) An adjustable etalon device further comprising a front stop structure that determines a minimum gap between the front mirror and the cap plate.
xvi) An adjustable etalon device that houses at least a portion of an actuation mechanism configured to control a gap dimension between a front mirror and a rear mirror.
xvii) the cap plate comprises at least one first electrode formed on a cap surface facing the frame structure, wherein the frame structure is configured to operate as a second electrode; An adjustable etalon device movable by electrostatic actuation using two electrodes.
xviii) A tunable etalon device, wherein the at least one first electrode includes a plurality of electrodes that are electrically isolated from each other.
xix) An adjustable etalon device further comprising a front stop structure that determines a minimum electrostatic gap between the frame structure and the at least one first electrode.
xx) The tunable etalon device having a transparent or translucent material, thereby providing a tunable etalon surrounded between two transmissive or semi-transparent plates. .
xxi) further comprising a Si layer serving as at least one first electrode, wherein the frame structure is configured to operate as a second electrode and is movable by electrostatic actuation using the first and second electrodes. Tunable etalon device.
xxii) A tunable etalon device wherein the Si layer is the handle layer of a silicon-on-insulator (SOI) wafer and the device is a "SOI device".
xxiii) the at least one first electrode includes a plurality of first electrodes formed on a handle layer of the SOI wafer, wherein the first electrodes are mechanically coupled to each other and are electrically insulated, adjustable Etalon device.
xxiv) further comprising a buried oxide (BOX) layer separating the Si layer from the frame structure, the BOX layer comprising a front mirror and a first electrode in a pre-stressed inactive device state; An adjustable etalon device having a thickness that determines an electrostatic gap between the etalon device.
xxv) An adjustable etalon device further comprising an opening in the handle layer of the SOI wafer to allow passage of light to the front and rear mirrors.
xxvi) An adjustable etalon device further comprising a first lens integrated with the rear mirror and a second lens integrated with the cap.
xxvii) Adjustable etalon according to any one of claims 19 to 22, or 24 to 27, further comprising a respective lens integrated with each of the front and rear mirrors. ·device.
xxviii) The adjustable etalon device according to any one of claims 19 to 22, or 24 to 27, further comprising a respective lens integrated with the rear mirror and the cap.
xxix) Any one of claims 2 to 22 or 24 to 27, wherein the gap in each of the first and second states allows light in a predetermined wavelength range to pass through the etalon. The tunable etalon device of claim 1.
xxx) The adjustable etalon device of claim 25, wherein the actuation gap dimension between the front and rear mirrors is defined by a front stop separating the frame structure and the cap.
xxxi) The actuation mechanism comprises a piezoelectric actuator.
xxxii) The actuation mechanism comprises a Kelvin Force actuation electrode.
xxxiii) An adjustable etalon device according to any one of claims 1 to 37, designed to assume one of a first state and a second state, The gaps in each of the states allow light in a predetermined wavelength range to pass through the etalon, and the first state has an initial pre-operation having a non-operating gap dimension between the front and rear mirrors. The stressed, non-operating state, wherein the non-operating gap dimension is defined by the rear stop, and the second state is that the gap dimension between the front mirror and the rear mirror is determined by the pre-stressed non-operating gap. An actuated condition having an actuation gap dimension that is greater than the actuation gap dimension.
xxxiv) The working gap dimension between the front and rear mirrors is defined by the front stop.

According to another aspect of the presently disclosed subject matter, there is provided an imaging device comprising:
a) an adjustable etalon device comprising a front mirror and a rear mirror, wherein the front mirror and the rear mirror are in a pre-stressed inactive state in an initial prestressed inactive state; An etalon spaced apart by a gap having a gap dimension, wherein the etalon is configured to assume at least one actuation state, the gap having a greater actuation gap dimension than a pre-stressed non-actuation gap dimension. A controller configured and operable to adjust the device b) the image sensor, and c) the adjustable etalon device to capture image data via the image sensor.

  An imaging device according to the presently disclosed subject matter, optionally with mutatis mutandis, one or more of features (i) through (xxxiv) listed above, in any desired combination or replacement. be able to.

  Non-limiting examples of the embodiments disclosed herein are described below with reference to the accompanying drawings, which are listed after this paragraph. The drawings and description are intended to illustrate and clarify the embodiments disclosed herein, and should not be considered as limiting in any way. The same elements in different drawings may be denoted by the same numerals.

1 is a schematic isometric view of a tunable MEMS etalon device, according to an example of the disclosed subject matter. 1B is a schematic cross-sectional view of the device of FIG. 1A, according to an example of the presently disclosed subject matter. FIG. 1B is an illustration of the device of FIG. 1B in an initial, as-manufactured, unstressed, inactive state, in accordance with an example of the disclosed subject matter. FIG. 2B is an illustration of the device of FIG. 2A in an initial, pre-stressed, inactive state, according to an example of the presently disclosed subject matter. FIG. 2B is a diagram of the device of FIG. 2B in an operational state, according to an example of the presently disclosed subject matter. 1B is a schematic top view of a functional mechanical layer in the device of FIG. 1A or 1B, according to an example of the presently disclosed subject matter. FIG. 1B is a schematic top view of a cap in the device of FIG. 1A or 1B with a plurality of electrodes formed thereon, according to an example of the presently disclosed subject matter. FIG. 1 is a schematic cross-sectional view of an adjustable, MEMS etalon device in an initial, as-manufactured, unstressed, inactive state, in accordance with an example of the presently disclosed subject matter. FIG. 5B is a diagram of the device of FIG. FIG. 5B is an illustration of the device of FIG. 5B in an actuated state, according to an example of the presently disclosed subject matter. 5B is a bottom view of the handle layer of the SOI wafer in the device of FIG. 5A or 5B, according to an example of the presently disclosed subject matter. FIG. 3 is an illustration of an assembly comprising a device disclosed herein, with integrated optics, in accordance with an example of the presently disclosed subject matter. 1 is a schematic block diagram of a sequential imaging system configured according to an example of the presently disclosed subject matter. FIG. 3 is a schematic diagram of stages in a manufacturing process of a GSG-type tunable MEMS etalon device disclosed herein, according to an example of the presently disclosed subject matter. FIG. 1 is a schematic cross-sectional view of an adjustable, MEMS etalon device in an initial, as-manufactured, unstressed, inactive state, in accordance with an example of the presently disclosed subject matter. 10B is an illustration of the device of FIG. FIG. 11B is a diagram of the device of FIG. 10B in an actuated state, according to an example of the presently disclosed subject matter.

  FIG. 1A schematically illustrates, in an isometric view, a first example of an adjustable MEMS etalon device disclosed herein and numbered 100. FIG. FIG. 1B shows an isometric cross-sectional view of device 100 along a plane marked AA. Device 100 is shown with an XYZ coordinate system that can also be applied to all of the following figures. FIGS. 2A, 2B, and 2C show three configurations (states): as-manufactured (unstressed) inoperative (FIG. 2A), and pre-stressed, inoperative. FIG. 2B shows a cross-sectional view of the device 100 in the plane AA in FIG. The device 100 comprises a bottom (or "rear") mirror 102, which is two substantially flat parallel mirrors / reflective surfaces, and a top (or "open") mirror 104 separated by a "rear" gap. . The terms “front” and “rear” as used herein reflect the orientation of the device towards the light beam.

  As shown, the front (top) mirror is the first mirror in the path of light rays entering the etalon. In one example, the mirror is formed on a flat plate or wafer (eg, glass) made of a material that is transparent or translucent to the desired range of wavelengths of light transmitted by the tunable etalon filter. . In the discussion that follows, the term "glass" is used as a general, non-limiting illustration. The term glass is not to be construed as limiting, but any material or material having a suitable transmission for light in the wavelength range necessary for the etalon and the image sensor to function in the desired manner. Note that other materials are also contemplated, including combinations of the following, for example, plastic, silica, germanium, or silicon (silicon is transparent for wavelengths of approximately 1-8 μm). As used herein, the term “plate”, “wafer” or “layer” has a thickness defined by two parallel planes, and has a width and length substantially greater than that thickness. Refers to a substantially two-dimensional structure. "Layer" may also refer to much thinner structures (up to nanometer thickness than typical micrometer thickness in other layers).

  In an embodiment, the rear mirror 102 is formed in a glass layer that also functions as a substrate for the device. In other embodiments, the rear mirror 102 may be formed of a “hybrid” plate or material such that a central portion (“aperture”) through which light rays pass is transparent to the wavelength of light (eg, glass) Made). The plate surrounding the opening, on the other hand, is made of a different material, for example silicon. The hybrid embodiment can increase the rigidity and strength of the mirror.

In Figure 2A, in the state as-produced, the rear gap between the front mirror and rear mirror has a marked dimensions g _0. In the inoperative state of FIG. 2B, the back gap has dimensions marked with g _1. The operating state of Figure 2C, the back gap, having marked dimensions g _2. The mirrors are movable with respect to each other so that the rear gap can be adjusted between a predetermined minimum (g _Mn ) gap dimension and a maximum (g _Mx ) gap dimension. In the particular coordinate system shown, it moves in the Z direction. Specifically, according to the specific example disclosed herein, the rear mirror 102 (facing the sensor side with respect to the front mirror) is fixed and the front mirror 104 (with respect to the rear mirror). (Facing the subject side) is movable. The gap dimensions are minimal in the pre-stressed, inactive state, and therefore g ₁ = g _Mn . The maximum rear gap dimension g _Mx corresponds to the “maximum” operating condition. Back gap has a value g ₂ between g _Mn and g _Mx, (contiguous range of more state even) number of operating states of course exist.

The device 100 further includes a first stopper structure (also referred to as a "rear stop") 106 disposed between the mirrors 102 and 104 in a manner that does not block light rays, which is designed to reach the image sensor. Is provided. The rear stopper 106 can be formed on either mirror. In the non-operational state of FIG. 2A, as manufactured, the two mirrors are positioned very close to each other, and the minimum gap distance g _Mn is defined by the rear stop 106, which functions as a movement limiter. A further function of the stop 106 is to prevent unwanted movement of the front mirror due to external shocks and vibrations. The rear stop 106 is designed to prevent contact between the mirrors and to ensure that g _Mn never goes to zero. If the size of the rear stops is small and they do not significantly obscure the optical signal, they may be located in the light aperture area. The position of the rear stop in the light aperture area can be optimized in such a way that the movement of the movable front mirror 104 is minimized. In one example, the rear stop 106 is made of a metal, such as a patterned Cr-Au layer, a Ti-Au layer, or a Ti-Pt layer. The degree of reflectivity / transmission of the top and rear mirrors is selected according to the desired spectral transmission characteristics of the etalon. According to some examples, each mirror is at least partially semi-reflective.

  Device 100 further includes a mounting frame structure (or simply “frame”) 108 having an opening (“opening”) 110. The frame 108 is made of a transparent or translucent material (eg, single crystal silicon) and is fixedly attached (eg, by bonding) to the front mirror 104. That is, the mirror 104 is “mounted” on the frame 108 and thus moves with the frame 108. The aperture 110 allows light rays to enter the etalon through the front mirror. Therefore, the front mirror is also called "aperture mirror".

In one example, the rear mirror 102 and, optionally, the front mirror 104 have a titanium oxide (TiO ₂ ) layer deposited on a glass layer / substrate. In certain instances, the devices disclosed herein can include one or more electrodes (not shown) formed on a surface of the rear mirror 102 that faces the frame 108, such as a rear mirror. To move the frame structure toward (and thereby move the front mirror). Alternative actuation mechanisms can be applied, for example, piezoelectric actuation, Kelvin force, and the like. As the front mirror moves toward or away from the rear mirror, the spectral transmission band profile of the etalon is adjusted.

  Device 100 further comprises an anchor structure (or simply "anchor") 112 made of a transparent or semi-transparent material (eg, single crystal silicon). Anchor 112 and frame 108 are attached to each other by a flex / hang structure. The suspension structure may be, for example, a bending or torsion spring, a combination of such springs, or a patterned doughnut-shaped membrane of a thin donut configured to carry a front mirror. It can be an area. In device 100, the suspension structure includes a plurality of suspension springs / bends. According to one example, in device 100, the plurality of suspension springs / bends includes four springs 114a, 114b, 114C, and 114d made of a transparent or semi-transparent material (eg, single crystal silicon). Prepare. The frame 108, the anchor 112, and the spring 114 together form a "functional mechanical layer" 300 shown in the top view of FIG. In the discussion that follows, the term “silicon” is used as a general, non-limiting example. The term silicon is not to be construed as limiting, but any material or combination of materials having the suitable flexibility and durability required for the bent structure to function in a desired manner; Note that other materials are also contemplated, including, for example, plastic or glass.

  2A-2C show that the surface of the front mirror 104 facing the incident light is attached to the frame 108. FIG. Different configurations of the front mirror 104 and the frame 108 will be described below with reference to FIG. FIG. 10 also shows that a flexure structure comprising four springs 114a, 114b, 114C and 114d (see FIG. 3) is attached to anchor 112 and frame structure 108, but not to the front mirror. It is shown that.

  In some instances, the frame 108 is separated from the rear mirror 102 by a spacer structure (or simply “spacer”) 116. According to one example, the spacer 116 can be formed of a glass material. Spacers 116 are used to separate the frame and spring from the plate on which mirror 102 is formed. In principle, the silicon anchor 112 can be attached directly to the bottom plate without the spacer 116, but this requires a very large deformation of the spring. In the geometry employed, this deformation exceeds the strength limit of the spring material, which requires the presence of the spacer layer 116. For technical reasons, in some instances, both the movable front mirror 104 and the spacer 116 are manufactured from the same glass plate (wafer). This simplifies manufacturing because the glass wafer and silicon wafer are bonded at the wafer level. For this reason, device 100 is referred to herein as a glass-silicon-glass (GSG) device.

Device 100 further includes a cap plate (or simply "cap") 118 that houses at least a portion of an actuation mechanism configured to control a gap size between the front and rear mirrors. As shown, the cap 118 is disposed on the subject side with respect to the front mirror 104 in the direction of the incident light. In an example of electrostatic actuation, the cap 118 houses an electrode 120 formed thereon or attached thereto (see FIGS. 2A-2C). The electrode 120 can be arranged, for example, on the bottom side of the cap 118 (facing the mirror). The electrode 120 is in permanent electrical contact with one or more bonding pads 126 located on the opposite (top) side of the cap 118 via one or more through glass vias 124. I have. The electrodes 120 are used to actuate the frame 108 (and thereby move the front mirror 104). The cap comprises a first recess (cavity) 119 for providing a “front” (also called “static”) gap d between the frame 108 and the electrode 120. In FIG. 2A is a structure of as-prepared (prior to bonding the device to the rear mirror), the gap d has the dimension d _0. After bonding, in the pre-stressed, inactive state shown in FIG. 2B, the gap d has a maximum dimension d _Mx . In any operating condition (as shown in FIG. 2C), the gap d has the dimension _{d 2.} Device 100 further includes a front stop 122 that separates between frame 108 and cap 118. In some instances, the front stop 122 electrically insulates the frame 108 from the cap electrode 120 (prevents an electrical short between the frame and the cap electrode). In one example, front stop 122 defines a maximum gap between front mirror 104 and rear mirror 102.

  In one example, the cap is made of a glass material. In other instances, cap 118 may be made of a "hybrid" plate or hybrid material (e.g., made of glass) such that the central portion ("aperture") through which light passes is transparent to the wavelength of light. . The plate surrounding the opening, on the other hand, is made of a different material, for example silicon. The hybrid embodiment can increase the rigidity and strength of the cap.

In some instances, particularly where imaging applications are of interest, the length L and width W of the mirrors 102 and 104 (FIG. 1A), on the other hand, allow light to pass through a relatively large multi-pixel image sensor. (Eg, on the order of hundreds of micrometers (μm) to several millimeters (mm)). On the other hand, the minimum gap g _Mn must be small enough to allow the desired spectral transmission properties of the etalon (eg, tens of nanometers (nm)). This results in a large aspect ratio of the optical cavity between the mirrors (eg, between the lateral dimensions W and L and the minimum gap distance g _Mn ), thereby causing the etalon to extend in its width / lateral spatial direction. In order to reduce or prevent spatial distortion of the color space transmission band along, it is necessary to maintain precise angular alignment between the mirrors. In some instances, g _Mn can have a value up to a minimum of 20 nanometers (nm), while g _Mx can have a value up to a maximum of 2 μm. According to one example, the value of g _Mx can be between 300 and 400 nm. Specific values depend on the required optical wavelength and are determined by the particular application. Thus, g _Mx may be one or two orders of magnitude greater than g _Mn . In one example, L and W may each be about 2 millimeters (mm), and spring 114 may be about 50 μm thick, about 30 μm wide, and about 1.4 mm long, respectively. Good. In one example, the thickness of the glass layers of the cap 118, the rear mirror 102, and the front mirror 104 may be about 200 μm. In one example, L = W.

  It should be understood that all dimensions are given by way of illustration only and should not be considered as limiting in any way.

  2A-2C provide additional information regarding the structure of the device 100 and some functions of its elements. As mentioned above, FIG. 2A shows the device 100 as it was at the time of initial manufacture and in a non-operated, unstressed state. In the state as manufactured, the front mirror 104 is not in contact with the rear stopper 106. FIG. 2B shows the device of FIG. 2A in an initial, pre-stressed, inactive state with the front mirror 104 physically contacting the rear stop 106. This physical contact occurs when the spacer layer 116 is forced into contact with the glass wafer substrate (including the rear mirror 102) to eutectically join the spacer 116 to the glass plate of the rear mirror 102. Is caused by the stress applied to the frame. See FIG. 9 (c) below. Thus, the configuration shown in FIG. 2B (and similarly in FIG. 5B) is said to be "pre-stressed." FIG. 2C shows the device in an active state in which the front mirror 104 at an intermediate position between the rear stop 106 and the front stop 122 moves away from the rear mirror 102.

In one example, the rear mirror 102 has a second recess 128 having a depth t designed to provide a pre-stress after assembly / bonding. According to one example, the depth t of the recess, on the one hand, the contact force caused by the deformation of the spring and the attachment of the movable front mirror 104 to the rear stop 106 is subject to shock and vibration during normal handling of the device. In some cases, it is selected to be large enough to maintain contact. On the other hand, in some instances, the value of the combination of the recess depth t plus the maximum required travel distance (maximum rear gap dimension) g _Mx is a stable and controllable electrostatic actuation of the frame by the electrodes located on the cap. The gap between the electrode 120 and the frame 108 is less than one-third of the as-fabricated (“electrostatic”) gap dimension d ₀ (FIG. 2A) to provide In some instances, electrostatic gap _{d 0} remains at the time of manufacture has a value of about 3 to 4 [mu] m, t may have a value of about 0.5 to 1 [mu] m. Stable moving distance of the capacitive actuator, 1/3 of the electrostatic gap left during production, i.e. for a _d 0/3, requirements for stable operation is _{t + g Mx <d 0/} 3.

  Note that in some instances, the inactive state may include a configuration where the movable mirror 104 is suspended and does not touch either the rear stop 106 or the front stop 122.

  In the actuated state shown in FIG. 2C, the mounting ring and the front mirror move away from the rear mirror. This is accomplished by applying a voltage V between one or more regions / electrodes 120 of the actuation substrate that serve as actuated electrodes and one or more regions of the frame 108.

  According to one example, device 100 is completely transparent. The device 100 comprises a transparent rear mirror (102), a transparent front mirror (104) and a transparent cap (118), and a transparent functional mechanical layer 300. One advantage of perfect transmission is that the device can be viewed optically from both sides. Another advantage is that this architecture may be useful for many other optical devices that incorporate movable mechanical / optical elements such as mirrors, gratings, or lenses. In one example, the device 100 is configured as a full glass structure, wherein the functional mechanical layer comprises a glass substrate that is patterned to house / define a suspension structure that carries an upper mirror. The structure has a plurality of glass springs / bends.

  FIG. 3 schematically shows a top view of the functional mechanical layer 300. This figure shows the outer contour 302 of the front mirror 104, the aperture 110, the anchor structure 112, the springs 114a-114d (bent structure), and the eutectic joint, which is described in further detail with reference to FIG. 4 below. A contour 304 surrounding the frame 121 and the cap spacer 122 is also shown.

  FIG. 4 schematically shows a top view of a cap 118 having a plurality of electrodes 120, here marked 120a, 120b, 120c and 120d. The number and shape of the electrodes 120 shown are shown by way of example only and should not be construed as limiting. According to one example, three electrodes 120 are needed to control both the movement of the frame in the Z direction and the tilt of the frame about the X and Y axes. For example, the plurality of electrode areas shown in FIG. 4 can operate the front mirror 104 with a degree of freedom (DOF) along the Z-direction and provide an additional angle DOF (eg, It can be fabricated on the cap 118 so that it can be tilted (with respect to the two axes X and Y). Thereby, the alignment of the angle between the front mirror 104 and the rear mirror 102 can be adjusted. According to some examples, cap 118 can have eutectic bonding material 121 deposited. In addition, the spacer 122 can be used to precisely control the electrostatic gap between the cap electrode 120 and the actuator frame 108 that functions as a second electrode. According to the subject matter of the present disclosure, the eutectic bonding material 121 can take the shape of a frame. In that case, the spacers 122 can be located on both sides (inside and outside) of the frame, thereby minimizing the bending moment acting on the cap as a result of the eutectic bond shrinking during the bonding process. it can.

The following is an example of how to use the device 100. The device 100 is activated to bring the etalon from an initial, pre-stressed, inactivated state (FIG. 2B) to an activated state (eg, as in FIG. 2C). Upon actuation, the frame 108 and the front mirror 104 move away from the rear mirror 102, widening the rear gap between the mirrors. An advantageous and stable control of the rear gap is made possible by an innovative design having an as-built (and unstressed) state of initial production. More specifically, this design is about three times the combination of the recess depth t and the maximum required travel (rear gap) dimension g _Mx , at the initial maximum as-manufactured (and (Unstressed) front gap dimension d ₀ (FIG. 2A). This is because the stable range of the parallel capacitor type electrostatic actuator is one third of the initial distance between the electrodes.

  According to one example, device 100 can be used as a preset filter for a particular application. For example, the device can be preset so that the gap between the mirrors in each of the two states (set by the stopper) assumes two different states, depending on the desired wavelength. For example, one state provides a filter that allows a first wavelength range to pass through the etalon, and the other state allows a second wavelength range to pass through the etalon. The design of such a "two-mode" filter is related to the simple and precise displacement of the mirror between the two states, which makes it possible to simplify the manufacturing.

According to one example, one state is an initial inactive etalon state g ₁ (the gap dimension between the mirrors is selected to allow the first wavelength range to pass through the etalon. a to) defined by the stopper 106, the other state, the gap is greater than the non-operation of the gap dimension given pre-stressed has an actuated gap size g _2, the front stopper 122 high resulted in electrical gap d ₂ equal to the second wavelength range is selected to allow passing through the etalon, which is an operating state. In the second state, the frame 108 is in contact with the front stopper 112.

  5A-5C schematically illustrate, in cross-section, a second example of a tunable MEMS etalon device disclosed herein and numbered 500. FIG. FIG. 5A shows the device 500 in an as-manufactured (unstressed) configuration before the spacer 116 is bonded to the rear mirror 102. FIG. 5B shows the device 500 in an initial, pre-stressed, inactive state, while FIG. 5C shows the device 500 in an active state. Device 500 uses SOI wafer and SOI fabrication techniques, and is therefore referred to herein as “SOI device”, in contrast to GSG device 100. Device 500 has a structure similar to that of device 100 and includes many of its elements (therefore, they are numbered the same). Since both SOI wafers and technology are known, the following uses the SOI terminology known in the art.

  In FIG. 5A, the front mirror 104 is not in physical contact with the rear stopper 106 on the rear mirror 102. However, in FIG. 5B, the front mirror 104 and the rear stopper 106 are physically separated by a given stress. Is in contact with In FIG. 5C, the front mirror 104 has moved away from the rear mirror 102 and is at an intermediate position between the rear stopper 106 and the electrode 520, where in an SOI device, the electrodes are at the handle layer 502 of the SOI wafer. Are made. SOI wafers are used so that the handle layer is useful not only as a substrate but also for manufacturing the electrodes 520. The frame 108 has a region functioning as a counter electrode. The anchor structure (layer) 112 in the device Si layer of the SOI wafer is connected to the frame 108 via springs 114a to 114d. The anchor structure 112 is attached to the handle layer 502 via the BOX layer 510. The gap between the Si device and the handle layer is shown at 530. Gap 530 is created by etching BOX layer 510 under the frame and under the spring. An opening 540 is formed in the handle layer 502 to expose the front mirror 104 and the rear mirror 102 to light rays in the −Z direction.

The remains of the time of manufacture, the spacer 116, before joining the glass plates containing the rear mirror 102, a gap 530 between the frame and the handle layer has dimensions d _0, as shown in FIG. 5A Equal to the thickness of the BOX layer. After bonding, the gap 530 has a dimension d _Mx equal to the thickness of the BOX layer 510 minus the depth t of the recess 128 and the height of the rear stopper 106. Thus, the spring is deformed when the front mirror 104 is in contact with the rear stopper 106, since the size of the gap 530 is released is reduced, due to the pre-stress, d _Mx is less than d _0. In operation of FIG. 5C, a frame 108, pull the front mirror 104 from the rear mirror 102, it is further reduced to _{d 2} the size of the gap 530, (up to the maximum dimensions of the back gap, to a maximum dimension _{g Mx} ).

  FIG. 6 is a schematic explanatory view of a bottom view of the handle layer of the SOI wafer. The figure shows the insulating grooves 602 between the electrodes 520. In some instances, one or more regions / electrodes 520 of the handle layer can have two or more regions that are substantially electrically isolated from each other. Thus, by applying different potentials between these two or more regions 520 of the handle layer and the region of the frame 108, it is possible to adjust the parallelism between the front and rear mirrors become. For example, the two or more regions of the handle layer are at least three regions arranged such that the parallelism between the front mirror and the rear mirror can be adjusted two-dimensionally with respect to two axes. Can be included.

  FIG. 7 shows a device comprising a lens 702 formed in or on the cap or attached to the cap, and a lens 704 formed in or on the rear mirror or attached to the rear mirror. FIG. 2 shows a schematic illustration of an assembly comprising 700. This allows the optical element to be integrated with the etalon to provide an "optical element integrated" adjustable etalon device. Again, if the inside of the cavity between the two glasses is under pressure, adding such a lens increases stiffness and reduces rear mirror and cap deformation. Other elements are as marked on device 100.

  In devices 100 and 500, the adjustable etalons disclosed herein can be used for imaging applications. For example, such a device can be used to convert a broad spectral band (eg, infrared (IR: infrared-IR) or near-infrared (NIR: near-IR) wavelengths on the long wavelength side of the spectrum to violet and / or short wavelength sides). Alternatively, it can be designed and used as a wide range of dynamic filters tunable over the visible (VIS) range up to the ultraviolet (UV) wavelength. Additionally or alternatively, such a device may be a broad spectral transmission profile (e.g., about 60-120 nm, full width half maximum (FWHM) of the spectral transmission profile), which may be an image acquisition / imaging. (Which is suitable for applications) and also has a relatively large free spectral range (FSR) between successive peaks, of the order of 30 nm or more, thereby allowing good color separation. Can be designed.

  The devices disclosed herein adjust the spectral transmission and other properties of the etalon using, for example, electrostatic actuation. The term "electrostatic" actuation is used to refer to a proximity gap actuation caused by the electrostatic force of a parallel plate between one or more electrodes on each of two layers of the device. For example, in the device 100, electrostatic actuation is performed by applying a voltage between one or more regions of the frame 108 and one or more electrodes 120 formed / deposited on the bottom surface of the cap 118. Is done. In the device 500, electrostatic actuation is performed by applying a voltage between one or more regions of the frame 108 and one or more regions of the handle layer 502. This achieves the adjustability of the movement between the mirrors and thereby the etalon.

One of the central issues of electrostatic actuation is the presence of so-called pull-in instability, in which approaching electrodes (e.g., mounting frames 108 of both device 100 and device 500) are stationary. Limit stable movement towards (eg, electrodes 120 or 520) to one third of the initial gap between the electrodes. Thus, in the electrostatically actuated configuration disclosed herein, the initial gap between the handle layer and the mounting frame or between the electrode 120 and the mounting frame is much larger than the required maximum optical gap _gMx. Large (at least 4-5 times). Therefore, the gap between the front and rear mirrors in the range from g _Mn to g _Mx is within the stable range of the actuator and the retraction instability is eliminated.

  As noted above, electrostatic actuation is just one example of an actuation mechanism used to adjust the gap between the front and rear mirrors, which is the MEMS etalon disclosed herein. Applicable to the device and should not be construed as limiting. The subject matter of the present disclosure further contemplates other types of actuation mechanisms, such as piezoelectric actuation and Kelvin force actuation.

  Specifically, in some instances, the etalon system may be configured such that the application of a voltage causes the frame structure to move away from the rear mirror (which results in the movement of the front mirror) or the frame or flexure. A piezoelectric actuation structure attached to the structure. In some instances, in operation, the frame 108 pulls the front mirror 104 away from the rear mirror 102, thereby increasing the size of the gap between the mirrors, and thus increasing the size of the rear gap. By placing several piezo-actuated structures on various parts / bends / springs of the frame, the parallelism between the etalon aperture mirror and the rear mirror can be controlled. U.S. Pat. No. 5,955,837, which is hereby incorporated by reference in its entirety, describes an example of embedding piezoelectric and Kelvin force operations. See, for example, FIGS. 8a-8c, 9a, and 9b.

  Referring now to FIG. 8, a sequential imaging system 800 configured in accordance with an embodiment disclosed herein is schematically illustrated in a block diagram. System 800 includes an image sensor 802 (eg, a multi-pixel sensor), and an adjustable MEMS etalon device 804 configured in accordance with the invention described above. The tunable MEMS etalon device 804 functions as a tunable spectral filter and is located in the general optical path of light propagation toward the sensor 802 (eg, intersects the Z axis in the figure). In some cases, an optical element 806 (eg, an imaging lens) is also located in the optical path of the sensor 802.

  The acquisition of a color image can be performed by device 800, for example, in a manner similar to that described in U.S. Patent No. 6,038,028, assigned to the assignee of the present application and incorporated herein by reference. . The tunable MEMS etalon device 804, when used in the imaging system 800, is configured to provide a spectral filtering profile suitable for sequential color imaging with high color fidelity.

  More specifically, according to various examples disclosed herein, the material of the etalon rear mirror 102 and the front mirror 108 and the size of the adjustable rear gap are such that the spectral filtration profile of the etalon is visible. The spectral range in the infrared / near-infrared region, which may be suitable for capturing color images, and in some cases (including colors corresponding to RGB space or hyper-spectral color space), may also be adjustable. Is composed of Also, the front and rear mirrors and the adjustable rear gap dimensions can be configured such that the transmission profile characteristics of the etalon (including, for example, FWHM and FSM) are also suitable for sequential color imaging. For example, the material of the front and rear mirrors and the adjustable rear gap size are such that the etalon's spectral transmission profile FWHM is wide enough to match the FWHM of the color in conventional RGB space. And so that the FSR between successive transmittance peaks in the spectral transmittance profile is large enough to avoid color mixing (simultaneous transmission to the sensor of different colors / spectral regions that the sensor can sense). To avoid). In addition, the etalon is relatively wide in the lateral direction (relative to the back gap dimension) and, as a result, is wide enough to intervene in the optical path between the optical element 806 and all pixels of the sensor 802. On the other hand, the gap between the mirrors is small enough to provide the desired spectral transmission characteristics and etalon tunability.

  The system 800 is also operably connected to the image sensor 802 and the adjustable MEMS etalon device 804, configured to adjust filters to capture image data, and so operable. Can be provided. For example, the capture of color image data can include the sequential acquisition of monochrome frames corresponding to various colors (various spectral profiles) from the sensor. For example, the controller 808 sequentially operates the adjustable MEMS etalon device 804 to sequentially filter light incident thereon using three or more different spectral filtering curves / profiles, and 3 By operating the sensor 802 to obtain three or more images (monochromatic images / frames) of light each filtered by one or more spectral curves, it can be configured to create / capture color image data. An adjustable spectral filter (Etalon device) 804 operates to maintain each of the spectral filtering curves at the corresponding time slot duration, while the sensor 802 adapts to each such time slot. It operates so as to capture each monochromatic image in the integration time of. Accordingly, each of the captured monochromatic images is filtered by a respective different spectral filtering curve and corresponds to light captured by sensor 802 over a predetermined integration time. The control circuit (e.g., a controller) further receives and processes the read data indicative of the three or more monochrome images from the sensor and processes the color image (i.e., the image including information regarding the intensity of at least three colors at each pixel of the image). ) Can be configured to generate data.

  The term "controller" as used herein, as disclosed herein below, is configured to execute instructions stored in, for example, a computer memory operably connected to the controller. Computer processor (eg, central processing unit (CPU), microprocessor, electronic circuit, integrated circuit (IC), digital signal processor (DSP), microcontroller, field programmable) Gate array (FPGA), application-specific integrated circuit (ASIC: application specific int) (including one or more of firmware written or ported for a particular processor, such as a graded circuit), and may be broadly construed to include any type of electronic device having data processing circuitry. .

  9 (a) -9 (s) schematically illustrate steps in a manufacturing process for a GSG-type tunable MEMS etalon device, such as device 100, according to one example of the presently disclosed subject matter. The process begins with a silicon-on-glass (SOG) wafer having a glass plate (also called a “glass wafer” or “glass layer”) 902 and a silicon device layer 904, as shown in FIG. 9 (a). The glass plate that will be used to form the upper movable mirror 104 and spacer 116 is first coated with an optical coating 906 (eg, titanium oxide), as shown in FIG. 9 (b). A metal layer is then deposited and lithographically patterned to serve as a solder material for eutectic bonding the spacer 116 to the bottom mirror 102, as shown in FIG. 9 (c). The SOG wafer is then turned over, and the Si device layer 904 is etched using deep reactive ion etching (DRIE) using a glass wafer used as an etch stop. Next, as shown in FIG. 9D, a frame structure 108 having an opening 110, an anchor structure 112, and a spring 114 is formed in the Si device layer 904. As shown in FIG. 9 (e), an antireflective (AR) coating 908 is deposited on the front (movable) mirror in the open area 110. Subsequently, as shown in FIG. 9F, the metal layer outside the region of the rear stopper 116 is removed and the glass is etched, so that the front movable mirror 104 and the stopper 116 are formed.

  As shown in FIG. 9 (g), processing of the cap wafer begins with the deposition of an AR coating on the surface of the cap glass wafer 118 facing the frame. After this step, a front stop 126 is patterned on the same surface of the cap wafer as shown in FIG. 9 (h). As shown in FIG. 9 (i), the AR coating on the cap wafer and the glass are partially etched as part of the formation of through glass vias 124. Next, as shown in FIG. 9 (j), a metal (eg, Cr—Au or Cu) is deposited in two steps to provide metallization for vias 124 and eutectic bonding of the cap wafer to Si anchor 112 To form a solder structure.

  As shown in FIG. 9 (k), the bottom glass wafer serving as the bottom mirror is first covered with an optical coating and the bottom stopper 106 is lithographically formed on the surface of the coating 916. As described above, and alternatively (not shown), in another process embodiment, bottom stop 106 may be lithographically formed on the surface of mirror 104. Next, the concave portion 128 of the glass wafer is formed in two steps of shallow etching shown in FIG. 9 (l) and then deep etching shown in FIG. 9 (m). Shallow etching is aimed at forming precise recesses that define the pre-stress of the spring, while deep etching is needed to provide space for soldering metals for eutectic bonding. As shown in FIG. 9 (n), a metal for eutectic bonding is deposited and patterned in the deeply etched glass region.

  As shown in FIG. 9 (o), using two eutectic bonding processes, the spacer 116 formed on the glass layer of the SOG wafer is bonded to the bottom glass wafer, and then the cap wafer is bonded to the SOG wafer. Bonded to the Si layer of the wafer. The cap wafer is then chemically and mechanically thinned to expose the partially etched vias 124, as shown in FIG. 9 (p). As shown in FIG. 9 (r), metal bonding pads 126 are formed on the top surface of the cap wafer by lithography. Finally, an additional AR coating is deposited and patterned in the open area on top of the cap wafer. A cross-sectional view of the completed, pre-stressed, inactive device is shown schematically in FIG. 9 (s).

  10A-10C schematically show, in cross-section, a third example of an adjustable MEMS etalon device disclosed herein and numbered 200. FIG.

  FIG. 10A shows device 200 in an as-manufactured (unstressed) configuration before anchor structure 112 is bonded to rear mirror 102. FIG. 10B shows the device 200 in an initial, pre-stressed, inactive state, while FIG. 10C shows the device 200 in an active state. Device 200 has a structure similar to that of device 100 and includes many of its elements (therefore, those elements are numbered the same).

  In one example, the front mirror 104 is a hybrid layer in which the front mirror is made of a transparent or translucent material (for a desired range of light wavelengths transmitted by a tunable etalon filter). And the structures of the anchor 112, the bend 114, and the frame 108 are made of a relatively rigid material. As shown in FIGS. 10A-10C, the front mirror is manufactured in alignment with frame 108 (eg, from a single wafer), rather than being mounted to the frame from one side. In some instances, the front mirror is made of any one of glass, plastic, or germanium. On the other hand, the structure of the anchor 112, the bent portion 114, and the frame 108 is made of silicon. Note that this list of materials is not exhaustive and should not be construed as limiting.

  In FIG. 10A, the front mirror 104 is not in physical contact with the rear stopper 106 on the rear mirror 102. However, in FIG. 10B, the front mirror 104 and the rear stopper 106 are physically separated by a given stress. Is in contact with In FIG. 10C, the front mirror 104 has been actuated to move away from the rear mirror 102 and is at an intermediate position between the rear stopper 106 and the electrode 120.

  In the state as manufactured, the front mirror 104 is not in contact with the rear stopper 106. FIG. 10B shows the device of FIG. 10A in an initial, pre-stressed, inactive state, with the front mirror 104 physically contacting the rear stop 106. This physical contact occurs when the springs are forced into contact with the glass wafer substrate (including the rear mirror 102) by the springs to effect a eutectic bond to the glass plate of the rear mirror 102. Caused by stress applied to the See FIG. 9 (c) below. In particular, the difference in height between the rear stop 106 and the anchor helps to achieve the required stress. Thus, the configuration shown in FIG. 10B is said to be "pre-stressed."

  FIG. 10C shows the device in an active state in which the front mirror 104 at an intermediate position between the rear stop 106 and the front stop 122 moves away from the rear mirror 102. In some instances, actuation is performed by applying a voltage V between one or more regions / electrodes 120 of the actuation substrate that serve as actuated electrodes and one or more regions of the frame 108. You.

As mentioned above, in some instances, the combined value of the maximum required travel distance (maximum rear gap dimension) g _Mx is to provide a stable and controllable electrostatic movement of the frame by electrodes located on the cap. , the gap between the electrode 120 and the frame 108, less than one third of the as-prepared ( "electrostatic") gap size _{d 0} (Figure 10A). In some instances, electrostatic gap d ₀ of as-produced has a value of about 2-4 [mu] m. Stable moving distance of the capacitive actuator, 1/3 of the electrostatic gap left during production, i.e. for a d _0/3, requirements for stable operation is g _{Mx <d 0/3.}

  Note that in some instances, the inactive state may include a configuration where the movable mirror 104 is suspended and does not touch either the rear stop 106 or the front stop 122.

  According to one example, device 200 is completely transparent. The device 200 comprises a transparent rear mirror (102), a transparent front mirror (104) and a transparent cap (118), and a transparent anchor 112, flexure 114, and frame 108 structure. One advantage of perfect transmission is that the device can be viewed optically from both sides. Another advantage is that this architecture may be useful for many other optical devices that incorporate movable mechanical / optical elements such as mirrors, gratings, or lenses.

  All patents and patent applications mentioned in this application are hereby incorporated by reference in their entirety for all the purposes set forth herein. It is emphasized that citation or identification of any reference in this application shall not be construed as an admission that such reference is available or acceptable as prior art.

  Although this disclosure has been described in terms of particular embodiments and generally associated methods, alterations and permutations of the embodiments and methods will be apparent to those skilled in the art. It is to be understood that this disclosure is not limited by the specific embodiments described herein, but only by the scope of the appended claims.

Claims (37)

  A front mirror and a rear mirror, wherein the front mirror and the rear mirror are separated by a gap having a pre-stressed non-working gap dimension in an initial pre-stressed non-working state. An adjustable etalon device, wherein the etalon is configured to assume at least one operating condition, wherein the gap has an operating gap dimension greater than the pre-stressed non-operating gap dimension.   The adjustable etalon device of claim 1, wherein the pre-stressed inactive gap dimension is determined by a rear stop structure in physical contact with the front mirror and the rear mirror. .   An anchor structure, a frame structure fixedly connected to the front mirror, and a bending structure attached to the anchor structure and the frame structure but not attached to the front mirror, The tunable etalon device of claim 1.   4. The tunable etalon device of claim 3, further comprising a spacer structure separating the anchor structure from the rear mirror.   5. The tunable etalon device of claim 4, wherein said front mirror and said spacer structure are formed in the same single layer.   6. The tunable etalon device of claim 5, wherein the single layer is made of any one of glass, plastic, silicon, and germanium.   4. The tunable etalon device of claim 3, wherein the anchor structure, the frame structure, and the flex structure are formed in the same single layer.   8. The tunable etalon device of claim 7, wherein the single layer is made of any one of glass, plastic, silicon, and germanium.   The tunable etalon device of claim 1, wherein the rear mirror is integrated into a layer made of a transparent or translucent material.   10. The tunable etalon device of claim 9, wherein the transparent or semi-transparent material is one of glass, plastic, silicon, and germanium.   10. The method of claim 9, wherein the transparent or semi-permeable layer further comprises a recess to assist in pre-stressing the flexure structure to enhance the pre-stressed inactive state. An adjustable etalon device as described.   The rear mirror may be configured such that a first of the at least two materials is transparent or semi-transparent, and a second of the at least two materials is more rigid than the first material. The tunable etalon device of claim 1, wherein the tunable etalon device is included in a hybrid structure having a combination of at least two materials.   13. The tunable etalon device of claim 12, wherein the different materials include glass and silicon.   2. The adjustable etalon device of claim 1, further comprising a cap plate located on the subject side with respect to the front mirror.   The adjustable etalon device of claim 14, further comprising a front stop structure that determines a minimum gap between the front mirror and a cap plate.   15. The adjustable etalon device of claim 14, wherein the cap plate houses at least a portion of an actuation mechanism configured to control a gap dimension between the front mirror and the rear mirror.   The cap plate comprises at least one first electrode formed on a cap surface facing a frame structure, wherein the frame structure is configured to operate as a second electrode; 15. The tunable etalon device of claim 14, wherein the etalon device is movable by electrostatic actuation using the second electrode.   18. The tunable etalon device of claim 17, wherein the at least one first electrode comprises a plurality of electrodes that are electrically isolated from one another.   The adjustable etalon device of claim 17, further comprising a front stop structure that determines a minimum electrostatic gap between the frame structure and the at least one first electrode.   15. The adjustment of claim 14, wherein the cap plate comprises a transparent or translucent material, thereby providing an adjustable etalon surrounded between two transparent or semi-transparent plates. Possible etalon devices.   21. The tunable etalon device of claim 20, wherein the transparent or semi-transparent material of the cap is any one of glass, plastic, silicon, and germanium.   The cap plate is permeable or semi-permeable for a first of the at least two materials and a second material of the at least two materials is more rigid than the first material. 15. The tunable etalon device of claim 14, wherein the tunable etalon device is made of a hybrid structure having a combination of the at least two materials.   The frame structure further comprises a Si layer functioning as the at least one first electrode, wherein the frame structure is configured to operate as a second electrode, and by electrostatic operation using the first and the second electrodes. 23. An adjustable etalon device according to any one of the preceding claims, wherein the etalon device is movable.   24. The tunable etalon device of claim 23, wherein the Si layer is a handle layer of a silicon-on-insulator (SOI) wafer.   The at least one first electrode includes a plurality of first electrodes formed on a handle layer of an SOI wafer, wherein the first electrodes are mechanically connected to each other and are electrically insulated. Item 24. The tunable etalon device of item 23.   A buried oxide (BOX) layer separating the Si layer from the frame structure, the BOX layer including the front mirror and the first mirror in the pre-stressed inactive device state; 24. The tunable etalon device of claim 23, having a thickness that determines an electrostatic gap between the electrodes.   24. The tunable etalon device of claim 23, further comprising an opening in a handle layer of the SOI wafer to allow light to pass through the front mirror and the rear mirror.   15. The adjustable etalon device of claim 14, further comprising a first lens integrated with the rear mirror, and a second lens integrated with the cap.   28. The adjustable etalon according to any one of claims 19 to 22, or 24 to 27, further comprising a respective lens integrated with each of the front mirror and the rear mirror. device.   28. An adjustable etalon device according to any one of claims 19 to 22, or 24 to 27, further comprising a respective lens integrated with the rear mirror and the cap.   28. Any of claims 2 to 22 or 24 to 27, wherein the gap in each of the first state and the second state allows light in a predetermined wavelength range to pass through the etalon. An adjustable etalon device according to claim 1.   26. The adjustable etalon device of claim 25, wherein the working gap dimension between the front mirror and the rear mirror is defined by a front stop separating the frame structure and the cap.   17. The adjustable etalon device of claim 16, wherein the actuation mechanism comprises a piezoelectric actuator.   17. The adjustable etalon device of claim 16, wherein the actuation mechanism comprises a Kelvin Force actuation electrode.   The gap in each of the first and second states is designed to assume one of a first state and a second state, such that light in a predetermined wavelength range passes through the etalon. Enabled, wherein the first state is the initial pre-stressed inactive state having an inactive gap dimension between the front mirror and the rear mirror; Is defined by the rear stop, wherein the second state is such that the gap dimension between the front mirror and the rear mirror is greater than the pre-stressed inactive gap dimension. 23. An adjustable etalon device according to any one of the preceding claims, wherein the etalon device is in an activated state.   36. The adjustable etalon device of claim 35, wherein the working gap dimension between the front mirror and the rear mirror is defined by a front stop. a) an adjustable etalon device comprising a front mirror and a rear mirror, wherein the front mirror and the rear mirror are in a pre-stressed non-actuated state in an initial, pre-stressed, inactive state; The etalon is configured to assume at least one actuation state separated by a gap having an actuation gap dimension, the gap having an actuation gap dimension greater than the pre-stressed non-actuation gap dimension. An adjustable etalon device,
b) an image sensor;
c) a controller configured to adjust the adjustable etalon device to capture image data via the image sensor and comprising a controller operable as such.